/**********************************************************************************************
 * Arduino PID Library - Version 1.2.1
 * by Brett Beauregard <br3ttb@gmail.com> brettbeauregard.com
 *
 * This Library is licensed under the MIT License
 **********************************************************************************************/

#if ARDUINO >= 100
#include "Arduino.h"
#else
#include "WProgram.h"
#endif

#include "PIDcontrol.h"

/*Constructor (...)*********************************************************
 *    The parameters specified here are those for which we can't set up
 *    reliable defaults, so we need to have the user set them.
 ***************************************************************************/
PIDcontrol::PIDcontrol(volatile double* Input, volatile double* Output, double* Setpoint,
                       double Kp, double Ki, double Kd, int POn, int ControllerDirection)
{
    myOutput = Output;
    myInput = Input;
    mySetpoint = Setpoint;
    inAuto = false;

    PIDcontrol::SetOutputLimits(0, 255);    //default output limit corresponds to the arduino pwm limits

    SampleTime = 100;                       //default Controller Sample Time is 0.1 seconds

    PIDcontrol::SetControllerDirection(ControllerDirection);
    PIDcontrol::SetTunings(Kp, Ki, Kd, POn);
}

/*Constructor (...)*********************************************************
 *    To allow backwards compatability for v1.1, or for people that just want
 *    to use Proportional on Error without explicitly saying so
 ***************************************************************************/

PIDcontrol::PIDcontrol(volatile double* Input, volatile double* Output, double* Setpoint,
                       double Kp, double Ki, double Kd, int ControllerDirection)
    :PIDcontrol::PIDcontrol(Input, Output, Setpoint, Kp, Ki, Kd, P_ON_E, ControllerDirection)
{
}

/* Compute() **********************************************************************
 *   This, as they say, is where the magic happens.  this function should be called
 *   every time "void loop()" executes.  the function will decide for itself whether a new
 *   pid Output needs to be computed.  returns true when the output is computed,
 *   false when nothing has been done.
 **********************************************************************************/
boolean PIDcontrol::Compute()
{
    if(!inAuto) return false;
    /*Compute all the working error variables*/
    double input = *myInput;
    double error = *mySetpoint - input;
    double dInput = (input - lastInput);
    outputSum+= (ki * error);

    /*Add Proportional on Measurement, if P_ON_M is specified*/
    if(!pOnE) outputSum -= kp * dInput;

    if(outputSum > outMax) outputSum = outMax;
    else if(outputSum < outMin) outputSum = outMin;

    /*Add Proportional on Error, if P_ON_E is specified*/
    double output;
    if(pOnE) output = kp * error;
    else output = 0;

    /*Compute Rest of PID Output*/
    output += outputSum - kd * dInput;

    if(output > outMax) output = outMax;
    else if(output < outMin) output = outMin;
    *myOutput = output;

    /*Remember some variables for next time*/
    lastInput = input;

    return true;
}

/* SetTunings(...)*************************************************************
 * This function allows the controller's dynamic performance to be adjusted.
 * it's called automatically from the constructor, but tunings can also
 * be adjusted on the fly during normal operation
 ******************************************************************************/
void PIDcontrol::SetTunings(double Kp, double Ki, double Kd, int POn)
{
    if (Kp<0 || Ki<0 || Kd<0) return;

    pOn = POn;
    pOnE = POn == P_ON_E;

    dispKp = Kp;
    dispKi = Ki;
    dispKd = Kd;

    double SampleTimeInSec = ((double)SampleTime)/1000;
    kp = Kp;
    ki = Ki * SampleTimeInSec;
    kd = Kd / SampleTimeInSec;

    if (controllerDirection == REVERSE)
    {
        kp = (0 - kp);
        ki = (0 - ki);
        kd = (0 - kd);
    }
}

/* SetTunings(...)*************************************************************
 * Set Tunings using the last-remembered POn setting
 ******************************************************************************/
void PIDcontrol::SetTunings(double Kp, double Ki, double Kd)
{
    SetTunings(Kp, Ki, Kd, pOn);
}

/* SetSampleTime(...) *********************************************************
 * sets the period, in Milliseconds, at which the calculation is performed
 ******************************************************************************/
void PIDcontrol::SetSampleTime(unsigned long NewSampleTime)
{
    if (NewSampleTime > 0)
    {
        double ratio  = (double)NewSampleTime / (double)SampleTime;
        ki *= ratio;
        kd /= ratio;
        SampleTime = NewSampleTime;
    }
}

/* SetOutputLimits(...)****************************************************
 *  This function will be used far more often than SetInputLimits.  while
 *  the input to the controller will generally be in the 0-1023 range (which is
 *  the default already,)  the output will be a little different.  maybe they'll
 *  be doing a time window and will need 0-8000 or something.  or maybe they'll
 *  want to clamp it from 0-125.  who knows.  at any rate, that can all be done
 *  here.
 **************************************************************************/
void PIDcontrol::SetOutputLimits(double Min, double Max)
{
    if(Min >= Max) return;
    outMin = Min;
    outMax = Max;

    if(inAuto)
    {
        if(*myOutput > outMax) *myOutput = outMax;
        else if(*myOutput < outMin) *myOutput = outMin;

        if(outputSum > outMax) outputSum= outMax;
        else if(outputSum < outMin) outputSum= outMin;
    }
}

/* SetMode(...)****************************************************************
 * Allows the controller Mode to be set to manual (0) or Automatic (non-zero)
 * when the transition from manual to auto occurs, the controller is
 * automatically initialized
 ******************************************************************************/
void PIDcontrol::SetMode(int Mode)
{
    bool newAuto = (Mode == AUTOMATIC);
    if(newAuto && !inAuto)
    {
        /*we just went from manual to auto*/
        PIDcontrol::Initialize();
    }
    inAuto = newAuto;
}

/* Initialize()****************************************************************
 *	does all the things that need to happen to ensure a bumpless transfer
 *  from manual to automatic mode.
 ******************************************************************************/
void PIDcontrol::Initialize()
{
    outputSum = *myOutput;
    lastInput = *myInput;
    if(outputSum > outMax) outputSum = outMax;
    else if(outputSum < outMin) outputSum = outMin;
}

/* SetControllerDirection(...)*************************************************
 * The PID will either be connected to a DIRECT acting process (+Output leads
 * to +Input) or a REVERSE acting process(+Output leads to -Input.)  we need to
 * know which one, because otherwise we may increase the output when we should
 * be decreasing.  This is called from the constructor.
 ******************************************************************************/
void PIDcontrol::SetControllerDirection(int Direction)
{
    if(inAuto && Direction !=controllerDirection)
    {
        kp = (0 - kp);
        ki = (0 - ki);
        kd = (0 - kd);
    }
    controllerDirection = Direction;
}

/* Status Funcions*************************************************************
 * Just because you set the Kp=-1 doesn't mean it actually happened.  these
 * functions query the internal state of the PID.  they're here for display
 * purposes.  this are the functions the PID Front-end uses for example
 ******************************************************************************/
double PIDcontrol::GetKp()
{
    return  dispKp;
}
double PIDcontrol::GetKi()
{
    return  dispKi;
}
double PIDcontrol::GetKd()
{
    return  dispKd;
}
int PIDcontrol::GetMode()
{
    return  inAuto ? AUTOMATIC : MANUAL;
}
int PIDcontrol::GetDirection()
{
    return controllerDirection;
}
